The reason why the temperature of the supermarket freezer can not fall and the decline is slow

It is a common phenomenon that the temperature of the supermarket freezer does not drop and the temperature drops slowly. Now I will briefly analyze the reasons for the slow temperature drop, hoping to bring a little help to my friends.

1. Due to poor insulation or sealing performance of the refrigerator, the loss of cooling capacity is large.

The reason why the insulation performance is poor is because the insulation layer of pipes, heat insulation boards, etc. is not thick enough, and the effect of heat insulation and heat preservation is not good. It is mainly caused by improper selection of the thickness of the insulation layer during design or poor quality of insulation materials during construction. . In addition, during the construction process, the thermal insulation moisture resistance of the thermal insulation material may be destroyed, causing the thermal insulation layer to be damp, deformed, or even smashed, and its thermal insulation capacity is reduced, the cooling loss is increased, and the temperature drop is obviously slowed down. Another important cause of large loss of cooling is poor sealing performance, with more hot air invading from the leak. Generally, if condensation occurs on the sealing strip of the door or the thermal insulation seal of the refrigerator, the sealing is not strict. In addition, frequent opening and closing doors or more people entering the warehouse together will also increase the cooling loss. Doors should be avoided as much as possible to prevent large amounts of hot air from entering. Of course, when the inventory is frequent or the quantity of goods is too large, the heat load increases sharply, and it takes a long time to cool down to the specified temperature.

Second, the surface of the evaporator is too thick or excessively dusty, and the heat transfer effect is reduced.

Another important cause of the slow temperature drop is the low heat transfer efficiency of the evaporator, which is mainly due to excessive frost or excessive dust on the surface of the evaporator. Since the surface temperature of the freezer evaporator is mostly lower than 0 ° C, and the humidity is relatively high, the moisture in the air is easily frosted on the surface of the evaporator, and even freezes, which affects the heat transfer effect of the evaporator. To prevent the surface of the evaporator from being too thick, it needs to be defrosted periodically.

Here are two simpler methods of defrost: 1 stop defrost. That is, stop the compressor operation, open the door, let the temperature rise, and then restart the compressor after the frost layer is automatically melted. 2 flushing cream. After the goods in the freezer are carried out, the surface of the evaporator tube is directly washed with tap water having a higher temperature to dissolve or fall off the frost layer. In addition to the excessive frosting, the heat transfer effect of the evaporator is not good. The surface of the evaporator is too thick for long-term uncleaning, and the heat transfer efficiency is also significantly reduced.

Third, there are more air or frozen oil in the supermarket freezer evaporator, the heat transfer effect is reduced. Once the inner surface of the heat transfer tube of the evaporator is attached with more refrigeration oil, the heat transfer coefficient will be reduced. Similarly, if heat transfer There is more air in the tube, the heat exchange area of ​​the evaporator is reduced, the heat transfer efficiency is also significantly reduced, and the temperature drop rate is slowed down. Therefore, in daily operation and maintenance, care should be taken to remove the oil on the inner surface of the evaporator heat transfer tube and exhaust the air in the evaporator in time to improve the heat transfer efficiency of the evaporator.

4. The throttle valve is improperly adjusted or blocked, and the refrigerant flow rate is too large or too small.

Improper adjustment or blockage of the throttle valve will directly affect the flow of refrigerant into the evaporator. When the opening degree of the throttle valve is too large, the refrigerant flow rate is too large, the evaporation pressure and the evaporation temperature also increase, and the temperature drop speed will be slowed down; meanwhile, when the throttle valve opening degree is too small or blocked, the refrigerant flow rate Also reduce, the cooling capacity of the system will also decrease, and the temperature drop of the warehouse will also slow down.

Generally, it can be judged whether the flow rate of the throttle valve refrigerant is appropriate by observing the evaporation pressure, the evaporation temperature, and the frosting condition of the suction pipe. Blockage of the throttle valve is an important factor affecting the flow rate of the refrigerant. The main cause of the blockage of the throttle valve is ice blockage and dirty blockage. The ice blockage is due to the poor drying effect of the dryer. The refrigerant contains moisture. When flowing through the throttle valve, the temperature drops below 0 °C, and the moisture in the refrigerant forms ice and blocks the throttle hole; the dirty plug is Due to the accumulation of more dirt on the filter inlet of the throttle valve, the refrigerant flows poorly and forms a blockage. China Kitchen Equipment Network